Physics & Chemistry

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Physics is the the study of matter and its spatial motion; while it embraces the levels of nucleii, elementary particles and atoms, its domain relative to molecules and their interactions is more properly termed chemistry. The motion of particles is governed by the basic laws of physics including Newtonian mechanics (for large objects); electromagnetism; thermodynamics and quantum mechanics (in the case of molecular and smaller entities). The earliest forms of physics addressed are motions of celestial objects, and presently this field can be viewed as astrophysics. Physics also embraces the notions of the Theory of Relativity, so that the duality of space and time is addressed. Chemistry has taken on added importance in the last half century as the bridge between fundamental laws of nature and the understanding of cellular processes and replication of DNA, the basic molecule of organism genetic coding.

Atmospheric lapse rate The atmospheric lapse rate (  ) refers to the change of an atmospheric variable with a change of altitude, the variable being temperature unless specified... More »

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Optical and acoustical phenomena in the Arctic Optical Phenomena In the Arctic, people frequently see unique and beautiful optical phenomena. The atmospheric conditions that can lead to the development of these... More »

Mercury (Physics & Chemistry) Mercury is a chemical element that occurs naturally in the environment and exists in several forms. Previous Element: Gold Next Element:... More »

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A Walk Through Time The Evolution of Time Measurement through the Ages. A Walk Through Time Ancient Calendars Celestial bodies — the Sun, Moon, planets, and stars — have... More »

DNA (Physics & Chemistry) Deoxyribonucleic acid (DNA) is a long chain organic molecule that contains the coding for all metabolic and reproductive processes of all living organisms, save for certain... More »

Global Challenges/Chemistry Solutions Global Challenges/Chemistry Solutions Global Challenges/Chemistry Solutions is a series of podcasts describing some of the 21st century's most daunting problems, and... More »

Hydrogen (Physics & Chemistry) Hydrogen has an atomic structure consisting of one proton and one electron, making it the lightest of the elements and exists as diatomic molecules. In the solid state the element... More »

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Uranium (Physics & Chemistry) Uranium is a radioactive element that occurs naturally in low concentrations (a few parts per million) in soil, rock, and surface and groundwater. It is the heaviest naturally... More »

Aluminum (Physics & Chemistry) Aluminum is a silver-white metal, very low density (less than three times as dense as water), yet relatively strong. In addition, aluminum is ductile; that is, it can be drawn... More »

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Nuclear power (Physics & Chemistry) Nuclear power is the generation of electricity from controlled reactions within the nucleii of atoms that release energy used to boil water, the steam from which drives a turbine to generate electricity . All commercial nuclear plants presently rely upon nuclear fission reactions. As of 2010, approximately 14 percent of the world's electricity was derived from nuclear power, chiefly centered in the United States (with 31% of the world's total nuclear power capacity), France (16%), and Japan (10%). The International Atomic Energy Agency (IAEA) reports that, as of November 21, 2012, there are 437 nuclear power reactors in operation in 30 countries, plus Taiwan. Another 64 reactors under construction in 14 countries which if operational today would increase the worldwide electrical generation capacity of nuclear power by 17%. One hundred and forty reactors have been permanently... More »

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Fluorine (Physics & Chemistry) Fluorine is a highly reactive chemical element with atomic symbol F. Having the atomic number nine, fluorine is the lightest halogen. Fluorine is a yellow-green gas whichdoes not occur as a free, unreacted element in the natural environment. Under conditions of standard temperature and pressure, elemental fluorine forms a diatomic molecule with chemical formula F2. Chemically, fluorine is one of the strongest known oxidizing agents, and even more reactive and hazardous than chlorine. Its very high electron affinity causes fluorine to react directly with almost all other elements except for several of the Noble gases. Previous Element: Oxygen Next Element: Neon 9 F 18.998 Physical Properties Color colorless Phase at Room Temp. gas Density... More »

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Concentration expressions and notations In chemistry and other sciences, engineering and in fairly common usage, concentration is the measure of how much of a given substance there is in a given mixture of substances. There are many different notations and quantitative expressions of concentration.[1] The most commonly used expressions are discussed below: The mole fraction is a measure of the concentration of a component substance in a mixture of substances. It is defined as the number of moles of a component substance in a mixture divided by the total number of moles of the mixture.[2][3] The mole percent (also referred to as the molar percent) is usually denoted by mole % and is equal to 100 times the mole fraction. The mass fraction is also a measure of the concentration of a component substance in a mixture of substances. It is defined as the mass of a component substance in a mixture divided by the total... More »

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Los Alamos National Laboratory Los Alamos National Laboratory (LANL), located in Los Alamos, New Mexico, is one of several U.S. Department of Energy (DOE) national laboratories. It is noteworthy as the site where the world's first nuclear weapon was developed under a heavy cloak of secrecy during World War II, and has been known variously as Site Y, Los Alamos Laboratory, and Los Alamos Scientific Laboratory. Today, it is recognized as one of the world's leading science and technology institutes. Since June 2006, LANL has been managed and operated by Los Alamos National Security, LLC (LANS).[1] LANL's self-stated mission is to ensure the safety, security, and reliability of the nation's nuclear deterrent.[2] Its research work serves to advance bioscience, chemistry, computer science, Earth and environmental sciences, materials science, and physics disciplines. The Manhattan Project was the... More »

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Photovoltaics (Physics & Chemistry) In recent decades the imminence of an energy crisis has become a common discussion topic. We will eventually deplete all fossil fuels that can be economically extracted.[1] Depletion is not the only issue involved in the use of fossil fuels; the combustion process releases carbon dioxide which can or is changing global climate. Fossil fuels, such as coal, natural gas, and oil, are the most common energy sources used today. When combusted to create energy, these fuels release large amounts of carbon dioxide and other greenhouse gases. These emissions cause a warming effect on the planet. The exact results of this warming are not certain, but most predictions verge on the catastrophic. In order to curb this warming effect and free ourselves from fossil fuel use, we must reduce, and ultimately replace, them as an energy source. One promising renewable energy source involves capturing... More »